DreamWorks separated into two companies, live action and animation, in 2004.
Disney and DreamsWorks Pictures (the live action comapny) had a distribution deal that ended earlier this year. This was films like Lincoln, The Help, Bridge of Spies. The new distribution deal has DreamWorks Pictures with Universal.
Because DreamWorks Animation is a separate company it was not under the distribution deal with Disney. In addition, the company was recently purchased by Comcast (Universal).